I've read quite a few previous posts, but they seemed either out of date or not quite pertinent to our situation. We are considering converting our oil steam boiler to natural gas. Natural gas has recently become available to us (we are the very last house on the line), and our oil-fired boiler has been pronounced moribund. It's not that old -- maybe 14 years -- and a very good brand, so I have to accept that poor maintenance is to blame. We have very hard water, and I sometimes let several months go by without purging the boiler. (Sorry. We knew nothing about radiators or steam at all when we bought the house 10 years ago.)
If we have to replace the boiler anyway, it seems prudent to consider converting to natural gas. I checked the fuel comparison chart recommended here, and it appears that natural gas is about a third of the price of fuel oil in our area per Btu. Gas boilers are more efficient, and I believe we may be eligible for a tax credit on that account.
We also have an oil-fired water heater. We'd need to switch that too, I guess, but I'm very confused about the pros and cons of indirect water heating from the boiler versus a stand-alone gas water heater. I thought indirect was a good idea when I first heard of it, but I've since heard that it adds to the gas costs.